Check obj exists before attempting to perform "querySelectorAll"

fixes: Uncaught TypeError: Cannot read property 'querySelectorAll' of undefined
when mail widget is used on dashboard and a user isn't logged in
Better fix
Clean up utils.js to avoid variable issues
Update Flickr expando regex; fixes #825
firefox survives saving data if store.json isn't created yet

e.g. first install, launching with fresh profile
technically it recovers from an exception loading the file, which hopefully won't lead to *more* data loss
@honestbleeps @SirCmpwn attn
Update user tagger to enable a "show anyway" option on ignored posts
cleanup
Merge pull request #855 from mc10/minor-fixes

Clean up utils.js to avoid variable issues
Merge pull request #856 from mc10/flickr

Update Flickr expando regex
Merge pull request #861 from thybag/feature/blocked-show-anyway

Add "show anyway" option on ignored posts
Merge pull request #860 from andytuba/simplestorage-firstrun

firefox survives saving data if store.json isn't created yet
fixed issue with empty store.json situation
Merge pull request #814 from thybag/bug/dashboard-mail-notloggedin

Fix (very) minor bug